Railroad track bed

ABSTRACT

A railroad track bed consists of a roadbed sealingly supporting a multiplicity of longitudinally interconnected concrete slabs and defining a space between the lateral supports and the slabs which is filled with a cellular resin or elastomer. The filling consists in whole or in part of preformed foamed synthetic resin bodies, preferably locked together in a continuous resin (foam) matrix.

O Umted States Patent 1 [111 3,756,507 Hiinig et al. Sept. 4, 1973 RAILROAD TRACK BED 3,432,098 3/1969 Sato 238/283 Inventors: siegtried g Paine; Karl Mienes, 3,451,621 6/1969 Splinter 238/283 Aachen. both of Germany FOREIGN PATENTS OR APPLICATIONS [73] Assignee; Stahlwerke Peine-Salzgiflen AG, 1,180,689 2/1970 Great Britain 238/2 Peine, Germany [22] Filed: Aug 4 1971 Primary ExaminerGerald M. Forlenza Assistant ExaminerRichard A. Bertsch PP NOJ 169,042 Attorney-Karl F. Ross [30] Foreign Application Priority Data [57] ABSTRACT Aug. 6, 1970 Germany P 20 39 033.4

A railroad track bed consists of a roadbed sealmgly 52 us. Cl. .Q. 238/2 suppming a multiplicity of Rmgiwdinally intercon- 51 lm. Cl E0lb 1/00 "ected Slabs and defining a space between [58] Field of Search 238/2 3 4 283 lateral SUPPMS and Slabs which is filled with a 2258/2322. lular resin or elastomer. The filling consists in whole or in part of preformed foamed synthetic resin bodies, [56] References Cited preferably locked together in a continuous resin UNITED STATES PATENTS (mam) 3,656,690 4/1972 Hanig 238/2 10 Claims, 10 Drawing Figures PAIENTEBSEP Man I 3.756501 SHEET 2 or 4 H'A'mc MIENES SIEGFRIED KARL I N VENTORS,

ATTORNEY i SIEGFRIED HKNIG KARL mamas INVENTORS' ATTORNEY PATENTEUSEP 4m 3756507 SHEET 0F 4 4|o SIEGFRIED HKNIG RAILROAD TRACK BED FIELD OF THE INVENTION BACKGROUND OF THE INVENTION In railroad track beds it has become a common practice to provide the railroad right of way with a layer. of

ballast (crushed stone, gravel or the like) in whichties or sleepers are partly embedded. The ties or sleepers.

carry the tracks. The ballast is intended to provide rapid draining of the bed, cushioned support' forthe.

sleepers or ties and the rails, and weathering-free retaining means preventing lateral movement of the rails.

with the sleepers. While sleepers or ties of wood; have found general application in the railway art, it has been proposed to substitute concrete sleepers or evento provide concrete railroad beds consisting of longitudinally interconnected slabs on which the rails are mounted. These arrangements have the advantage that the slabs are weather resistant and provide a secure anchorage. for the rails to accommodate high-speed trains. On the other hand, it hasbeen necessary heretofore toprovide special foundations for such slabs and specially designed sealing means for preventing the accumulation of moisture below the slabs and leaving damageto. the slabs because of freezing of accumulated moisture.

We may also mention the fact that conventionalslah construction has not been adaptable simply, and, conveniently to earlier ballast-type roadbeds. Disposal. of theballast and a complete reworking of the bed was often.

required.

OBJECTS OF THE INVENTION It is the principal object of the present invention to provide a railroad bed which is capable of obviating the aforementioned disadvantages.

It is yet another object of the invention to provide an improved railroad bed of the concrete-slab type in which an existing roadbed structure can be incorporated and the assembly made resistant to weathering and especially frost.

SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter are attained in accordance with the present invention, with a concrete-slab railroad. bed consisting of a plurality of longitudinally interconnected railsupporting concrete slabs, sealed along their longitudinal edges against or with respect to a foundation surface and defining a cavity with this foundation surface between the longitudinal edges and spanned by the major part of the width of the slab. The invention resides in the introduction into this compartment, chamber or space of a mass of load-supporting hollow bodies filled with a foamed synthetic resin which may be interconnected by a matrix of synthetic resin to provide a yieldable support for the body of the slab. The filling, especially when retained in a synthetic-resin matrix, is impermeable to moisture and unaffected thereby and thus is resistant to heaving under freezing conditions.

The hollow bodies according to the present invention may be pillows or blankets formed by a synthetic-resin foil to be positioned, by themselves, as units within the space below the slabs. Alternatively, they may be part a foamedsynthetic resin along the underside of the slab and to provide the pillow orv blanket in the form of a foil underlying this layer such that the compartment between the foil and "the layer is filled with foamed synthetic resin. One or, more such'pillows'or blankets may be providedacross the width and/or length of each slab and we may fill any spaces between. the blanket and within the compartment defined between the slab and the support surfacewith,additionalsynthetic resin preferably, of the foaming type,

According to this invention, moreover, the preformed pillows or blanketsand/or the pillow or blanket formed in situ withathe aforementioned synthetic-resin foil, may, be filled, in turn with foamed synthetic resin and/ora mixture of foam-filled'bodies and foamed synthetic resin..

Alternatively, the foam-filled hollow bodies may simply be introduced into thespace between the concrete slab, and the synthetic-resin surface (without interposition of a foil), although itispreferred to bind the foamfilled bodiesin a synthetic-resin matrix, preferably of a foaming synthetic-resimln all cases, the foam bodies fill the spacebetween the slab and the support surface and adjust oraccommodate to the, configuration of the support surface. The foam bodies according to the invention may be; pouches. or bags of synthetic-resinfoil filled, in turn, with afoamed synthetic resin or merely introduced into the space between the slab and the support surface, or into a pillow or blanket disposed between the slabv and the support surface.

Alternatively, the foam-filled bodies may be balls of inflated foil or elastomeric members (e.g., balloons) filled with foamed synthetic resin, or blown syntheticresin bodies, having a sealed or densified outer shell and a cellular core.

In other words, the present invention provides, as a support for the rails of a roadbed, concrete plates or slabs of rectangular configuration which are longitudinally interconnected and are preferably mounted upon a bed of ballast or gravel as a roadbed after cementing of the ballast and the provision of a foundation for the slab. This foundation is preferably a pair of longitudinal ridges Between the ballast and the concrete slab, or between any other supporting surfaces of the slab between the ridges, there is a space which is filled with one or more hollow bodies consisting of foamed synthetic-resin or a foamed-resin/solid body mixture such that the filling accommodates itself to the shape of the space. The hollow bodies can be pre-formed, but preferably consist of single or multiple pouches, balls or balloons which may be filled with foamed synthetic resin or epoxy, held in place by a hinder or a foamed synthetic resin. The bodies may be unitarily formed from synthetic resin with a cellular core and a densified outer shell.

Instead of a single foam pouch filling the entire space between the support surfaces of the concrete slab, we

emulsion so that, upon polymerization, the water is bound in the synthetic-resin matrix.

We have found it to be advantageous, moreover, to provide directly below the concrete slab an elastic layer or plate of synthetic-resin material which, in turn, may be provided with foam-fillable foil forming a bag with this layer, the filler, in this case, preferably to be either cellular material alone or a cellular material alone or a cellular synthetic resin filled into hollow bodies which are introduced into the space below the cushion layer. The cushion layer preferably will be a pre-formed slab of a foamed synthetic resin, preferably a polyester foam which may be reinforced with cellular-glass particles, fiberglass, or the like, thereby forming a matrix for the hollow bodies; it may likewise be a polyethylene resin or a polyester resin concrete. We prefer to employ the former since it can be mixed with blown-glass bodies or other reinforcing and filling materials in a conventional cement mixer at the railbed site. The polyurethane foam has a greater pot life or hardening time and thus is preferable to the polyester of short pot life.

The binder need not be reactive foam capable of bonding to the hollow bodies or to the concrete and the support surfaces, but may be so reactive if so desired. Here again we prefer to use polyurethane materials. Other suitable binders are epoxy resins and polyester concretes which may be provided with hollow glass balls, expanded glass or glass fiber as fillers. When the synthetic resin of the fillers and the synthetic resin of the hollow bodies, foils and cushion layers are of similar or chemically interactive materials, the entire mass beneath the concrete slab is of a unitary and structurally monolithic construction.

We also contemplate, within the ambit of the present invention, the use of prefoamed bodies, for example pre-expanded polystyrene beads which may be introduced as a loose filler into the space between the concrete slab and the support surface. These beads may be expanded in situ to fill the space and bond the particles together. Expansion in this matter may be accomplished by introducing steam into the space between the slab and the ballast bed which provide a form in which the beads are expanded. Preexpanded polystyrene beads may also be mixed with liquid epoxy resin and introduced into a slurry between the ballast and the concrete slabs and foamed and/or hardened in place.

An elastic junction between the concrete slabs and the ballast is provided by the aforedescribed system and by incorporation into the synthetic resin mass filling the space, of various elastic particles such as flakes of foamed synthetic resins (alone or in combination with solid or hollow particles), for example a crosslinked polyethylene foam or chopped or ground polystyrene foils. Alternatively any ceramic or other filler may be used in conjunction therewith. When the foil is provided as a loose covering on the underside of the concrete slab and the space between the bottom of the slab and the foil is filled with the solid or hollow bodies of the foamed resin or other material in admixture with the foaming binder, or a foamed preformed plate partially fills the space, there is the advantage that relatively little foam binder need be introduced into the space, especially if the space or bag is partly filled with the hollow bodies. The construction process is thereby made more rapid. There is, however, a slight danger that the foaming or injection of the binder will tear the foil.

When synthetic resin slabs are provided between the hollow bodies and the concrete slabs, they are preferably composed of cellular polyurethane elastomers.

DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a transverse cross section through a portion of the railroad bed embodying the present invention;

FIG. 2 is a similar cross section of an embodiment of the present invetion wherein a synthetic-resin slab is provided between the foil pocket and the slab;

FIG. 3 is a similar view of a roadbed which omits the layer of ballast;

FIG. 4 is a fragmentary transverse vertical cross section illustrating another embodiment of the invention;

FIG. 5 is a cross sectional view through a foam-filled ball according to the invention;

FIG. 5A is a cross section illustrating still another bag configuration according to the invention;

FIG. 6 is a sectional view through a foam pouch according to the invention;

FIG. 6A is a section through another hollow body incorporated in the roadbed;

FIG. 7 is a diagrammatic plan view of the roadbed embodying the invention; and

FIG. 8 is a cross sectional view through another portion of the roadbed according to our invention.

SPECIFIC DESCRIPTION In FIG. 1, we have shown a roadbed l which comprises upon the usual graded earth surface F, a mass of ballast, removed from an earlier roadbed, cleaned, and piled to a depth d 30 cm to form the crown of the bed. The ballast l is retained between a pair of ridges 2 extending longitudinally along opposite edges of the roadbed and having upwardly converging cross sections. The ridges 2 are formed from concrete or by a mixture of ballast with a mortar and are, therefore, sealed against penetration of moisture through the system. The upper surfaces 3 of ridges 2 are flat and receive rubber sealing strips 4 upon which concrete slabs 10 are mounted. As shown in FIG. 7, the concrete slabs are longitudinally interconnected in a rectangular configuration.

Below the surface of slab 10 and above a supporting surface la of the ballast bed, there is formed a space-5 which receives a pouch 13 of a synthetic-resin foil. The pouch is flexible and, as can be seen from FIG. 1, adjusts to fill the space 5 and contains cellular bodies 9 in the form of inflated members 20 in a syntheticresin (preferably foamed), reinforced-concrete or like binder 11. Preferably, the pocket 13 is placed in position before the foamed-resin filler 20, ll solidifies. In applying the slab 10, or the pouch or sack l3, care is taken to drive all air out of the subslab space. Of course, the foam mixture may be injected into the sack 13 after the latter has been placed inthe space 5 or after the latter has been filled at a location remote from the railbed, with some of the hollow bodies 20. Injection of the resin mixture may be carried out in the manner shown in the commonly assigned application Ser. No. 21,953 filed Mar. 23, I970 by Siegfried H'ainig, one of the present joint inventors (now U.S. Pat. No. 3,656,690).

Advantageously, the sack containing the hollow bodies is placed in position above the ballast 1, the slab is disposed thereabove, and a synthetic-resin binder of self-hardenable material, e.g., epoxy resin or a polyurethane foam, with its catalyst. The mass then expands to fit against the ballast and the slab 10.

In the system of FIG. 2, a synthetic-resin plate 15, e.g., a glass-reinforced polyurethane foam, is cemented to the surface of the concrete slab 110 to rest upon the sealing strips 104 which, in turn, are provided along the surface 103 of the ridges 102. Between the ballast 101 and the surface of this synthetic-resin plate 15, is provided a foil sack 16 partly filled with hollow bodies 111 as will be described in greater detail hereinafter. The sack 16 is formed by sealing the outer edges 22 of a foil 21 to the plate along the outer portions of concrete slab 110. Between the underside 17 of the foil 21, therefore, there is produced a space having a height of about 1 cm and filling the interior of the pouch. A synthetic-resin foaming mixture may be injected, as previously discussed.

Alternatively, the hollow bodies 111 may be polystyrene beads or pellets which are pre-expanded and subjected to heat treatment to densify the outer skin of these bodies. As soon as the slab and the outer foil are in place, steam can be introduced into the ballast bed to foam the synthetic-resin to fill any remaining gap between the synthetic-resin plate and the ballast. This sytem has the advantage that the major portion of the space can be filled by pre-formed synthetic-resin plates, thereby minimizing the extent to which the synthetic-resin within the sack must expand. This also reduces the amount of foaming mixture which must be introduced.

In FIG. 3, we have shown an embodiment of the present invention wherein the space 217 between the supporting surfaces 201a and the slab 210 is filled with two pouches 216 of a synthetic-resin foil which, in turn, are filled with hollow bodies 211 and a foaming mixture. In this embodiment, the foundation is formed with the ballast and the sealing strips 204 are provided directly upon the foundation and seal against the foamed synthetic-resin plate 215. The latter partly fills the space between a pair of supporting piers 202, the underside of the slab 210 and the upper surfaces 201a of the foundation 201. In the spaces around the sacks, a heatable synthetic-resin 225 is introduced, preferably in a mixture with foam particles, shavings or bodies. In all of the embodiments described above, the rails 12, 112 and 212 are mounted upon the concrete slabs in the usual manner.

In FIG. 4 we have shown an arrangement in which a plurality of pouches 316a, 316b are fromed along the underside of a concrete slab 310 by sealing the edges 316a, 316a", 316b', etc. to the underside 310a of the slab. A sealing strip 304 may here be provided above the edge 316a, the pouches are filled with hollow bodies 311a, 311b, the former being, in turn, pockets of a synthetic-resin foil 31 1b filled with a foamed or foamable synthetic resin 3l1b" which, in turn, may include foamed or inflated particles 31 1c in a foam-resin matrix 311d. The pocket 311b is shown in detail in FIG. 6. An alternative to this hollow foam-filled body is shown in FIG. 6A in which the hollow body 311a is shown to be empty and to have been inflated prior to incorporation into the cushion underlying the slab. The balls 3110 of FIG. 4 may have the configuration illustrated in FIG. 5

and thus may be formed of a foamed synthetic resin whose highly expanded cellular core 31 1a is unitary or integral (monolithic) with a densified shell 311a" Alternatively, an inflated foil ball 31lf may be employed as shown in FIG. 6.

In the embodiment of FIG. 8, the slab 410 again rests via seals 404 upon ridges 402 flanking the ballast 401. In this embodiment, loose expandable beads or pellets 411 are introduced into the space 405 and are foamed in situ by the introduction of steam into the ballast bed (see application Ser. No. 21,953). Thereafter, or, in addition, a synthetic-resin matrix 411a of a hardenable resin is introduced. Foil pockets are here avoided.

FIG. 7 shows, in plan view, a plurality of plates 510, 510' interconnected at 530 with any gap filled with a sealer 531. Plates 532 mount the rails 512 upon the concrete slabs which, in turn, are mounted upon ridges 502 confining the ballast between them. A pocket of foamed synthetic resin 511 in which hollow bodies 51 1 are anchored, is provided between the ballast and the concrete slabs.

We claim:

1. A railroad bed comprising:

a bed of ballast forming a generally horizontal support surface;

a plurality of horizontally interconnected generally rectangular concrete slabs spacedly overlying said support surface formed by said bed of ballast; cushion means substantially filling the space between said slabs and said surface and in contact at least with said bed of ballast, said cushion means being formed at least in part by at least one a hollow body filled with a foamed synthetic resin, said hollow body having a flexible outer skin around said foamed synthetic resin; and

a pair of rails mounted on the upper side of said con crete slabs.

2. The railroad bed defined in claim 1 wherein a multiplicity of such hollow bodies are provided in said space, said bed further comprising a synthetic resin matrix joining said hollow bodies together.

3. The railroad bed defined in claim 1 wherein said slabs are provided along their undersides with a synthetic resin plate extending into said space and forming part of said cushion means.

4. The railroad bed defined in claim 3, wherein said plate consists of a cellular polyurethane.

5. The railroad bed defined in claim 3, wherein said hollow bodies include a foil sealed along its edges to said plate and defining a pouch for a foamed synthetic resin.

6. The railroad bed defined in claim 1 wherein said hollow body is a flexible synthetic-resin foil pouch filled with foamed synthetic resin.

7. The railroad bed defined in claim 6 wherein-said pouch. is filled with a mixture of hollow elements and a foamed synthetic-resin binder.

8. The railroad bed defined in claim 1 wherein said hollow body is a foamed synthetic-resin ball provided with a densified skin.

9. The railroad bed defined in claim 1 wherein said hollow body is an inflated balloon.

10. The railroad bed defined in claim 1 wherein said space is filled with a multiplicity of hollow bodies foamed in situ and bonded together. 

1. A railroad bed comprising: a bed of ballast forming a generally horizontal support surface; a plurality of horizontally interconnected generally rectangular concrete slabs spacedly overlying said support surface formed by said bed of ballast; cushion means substantially filling the space between said slabs and said surface and in contact at least with said bed of ballast, said cushion means being formed at least in part by at least one a hollow body filled with a foamed synthetic resin, said hollow body having a flexible outer skin around said foamed synthetic resin; and a pair of rails mounted on the upper side of said concrete slabs.
 2. The railroad bed defined in claim 1 wherein a multiplicity of such hollow bodies are provided in said space, said bed further comprising a synthetic resin matrix joining said hollow bodies together.
 3. The railroad bed defined in claim 1 wherein said slabs are provided along their undersides with a synthetic resin plate extending into said space and forming part of said cushion means.
 4. The railroad bed defined in claim 3, wherein said plate consists of a cellular polyurethane.
 5. The railroad bed defined in claim 3, wherein said hollow bodies include a foil sealed along its edges to said plate and defining a pouch for a foamed synthetic resin.
 6. The railroad bed defined in claim 1 wherein said hollow body is a flexible synthetic-resin foil pouch filled with foamed synthetic resin.
 7. The railroad bed defined in claim 6 wherein said pouch is filled with a mixture of hollow elements and a foamed synthetic-resin binder.
 8. The railroad bed defined in claim 1 wherein said hollow body is a foamed synthetic-resin ball provided with a densified skin.
 9. The railroad bed defined in claim 1 wherein said hollow body is an inflated balloon.
 10. The railroad bed defined in claim 1 wherein said space is filled with a multiplicity of hollow bodies foamed in situ and bonded together. 